Skip to main content

Vitamin

Vitamin K

Also known as: K1, Phylloquinone, Phytonadione, Vitamin K

A
Evidence

A fat-soluble vitamin essential for blood clotting, bone metabolism, and cardiovascular health. Phytonadione (K1) is the plant-derived form found in leafy greens and the primary supplemental form.

Primary uses

  • Blood clotting
  • Coagulation support
  • Blood clotting support
  • Bone health and mineralization
  • Cardiovascular health
  • Protein carboxylation

How it works

  • Essential cofactor for clotting factors II, VII, IX, X
  • Rapidly cleared from circulation
  • Converts to MK-4 in some tissues

Dosage

Typical range
90-120 mcg daily (RDA)
Timing
With fat
With food
Yes
Duration
Usually adequate from diet
Special populations
Those on warfarin need consistent intake

Forms

  • Tablet
  • Phytonadione (K1)· 70/100
  • Menaquinone (K2)· 70/100
  • Phylloquinone· 70/100

Safety

Common side effects

  • Very safe

Contraindications

  • Warfarin users (without physician guidance)
  • Other vitamin K antagonist anticoagulants

Known interactions

Evidence notes

Essential for coagulation

Grade A: Multiple well-designed human trials support the main claims.

Related in Vitamin

Check a full stack

Formulate's free interaction checker lets you paste in any combination of supplements and medications at once — every pairing flags severity, timing, and cited evidence.

Open the checker

Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider.